1. Field of the Invention
The present invention relates generally to the field of microcomputing, and, more particularly, to an apparatus and method for minimizing electromagnetic interference in microcomputing systems.
2. Description of the Related Art
In the field of microcomputing, an increasingly high premium is placed on maximizing processing speed. One of the major limitations when attempting to increase processing speed is the emission of electromagnetic interference (EMI) from the microprocessors employed in such microcomputing systems. EMI is a speed limiting factor in microcomputing systems because it has a tendency to create unwanted high-frequency current loops in the motherboard of the microcomputing system. More specifically, the unwanted current loops on the motherboard emit high-frequency EMI known to interfere with the communications frequencies regulated by the Federal Communications Commission (FCC). To avoid running afoul of FCC regulations against interfering with communications frequencies, it may be necessary to limit the speed at which microprocessors are operated so as to curtail the amount of high-frequency EMI.
Various efforts have been undertaken in the prior art to combat the problem of EMI in microcomputing systems. One approach calls for providing the various conductor traces on the motherboard in a special layout so as to minimize EMI. However, this special trace routing is disadvantageous in that it consumes a fair amount of space on the motherboard, which, as will be appreciated, cuts against the overall goal of minimizing the size of microcomputing systems. Another approach involves adding local decoupling capacitors along the input lines of the microprocessor for the purpose of minimizing EMI. This approach is also problematic in that it is costly in terms of both space and money, and, furthermore, is ineffective at thwarting high frequency EMI. A still further approach involves employing multiple-layer motherboards specifically designed to minimize the amount of EMI. While such multi-layer motherboards are generally effective at minimizing EMI, the concomitant high cost of manufacture is a strong deterrent to any widespread acceptance.
Perhaps the most common technique for controlling EMI involves constructing the chassis of the microcomputing systems from a metal shield material such that any EMI generated by the motherboard and microprocessor is contained within the chassis structure. The main drawback of this technique is that high frequency EMI can readily escape from the vent openings required for cooling the microcomputing systems. Each of the foregoing prior art approaches fails in at least one significant respect, thereby precipitating the need for an improved apparatus and method for reducing EMI in microcomputing systems.
The present invention is directed at overcoming, or at least reducing the effects of, one or more of the problems set forth above.